And henry e



(No Model.)

W. H. ELKINS. REGULATOR FOR DYNAMO S. No. 427,163. Patented May 6, 1890.-

H EEEEE. Q IEP/EQlEIl T UNITED STATES PATENT OFFICE.

WVILLIAM H. ELKINS, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOB TO ALFRED D. TINGLEY, OF BOSTON, MASSACHUSETTS, AND HENRY E. IRVINE, OF

NEWV YORK, N. Y.

REG U LATO R F R DYNAMOS.

SPECIFICATION forming part of Letters Patent No. 427,163, dated May 6, 1890.

Application filed March 23, 1889. Serial No. 304,503. (No model.)

To all whom it may concern.-

Be it known that 1, WILLIAM HENRY ELF KINs, of Cambridge, in the county of MiddleseX and State of Massachusetts, have invented a new and useful Regulator for Dynamos, of

which the following is a specification, referenee being had to the accompanying drawin g, which is a diagram illustrating my invention, the pole-pieces and cores being shown in dotted lines, and the circuit, which constitutes the main novelty, being shown in full lines.

My invention relates to regulating the potential of the work-circuit of a dynamo; and it consists in a novel compound dynamo-circuit diflt'ering materially from all other dynamoeircuits known to me, as will 110w be fully explained.

In the drawing, A represents the armature, and a the commutator, of an ordinary dynamo; B, the positive brush, and B the negative brush, and B an additional brush, the workeircuit being from the additional brush B through the junction 19 and lamps L L to main brush B. Conductors lead from junction 1) to the additional brush B and also to the main brush B through resistance R, this circuit from brush B through resistance R to junction 1) being the regulating-circuit.

In practical operation it is necessary to preserve a constant pressure or potential in the work-circuit B L L b, the eurrentvarying as the number of lamps L varies. In the dia gram I have shown five lamps or groups of lamps, so that the variable load may be divided into five portions. It will be found that the brush B may be so adjusted in any given dynamo with a given speed that the desired pressure will be maintained over the workcircuit B L L b when only one lamp out of the five-that is, one-fifth of the variable loadis used, the regulating-circuit B B I) being then open, or, what is practically the same thing, the resistance B being very large. Under total number of lamps, will not be at full candle-power. To remedy this the electro-motive force or pressure in the work-circuitB L L I) must be brought up to the standard. Avolt- 5 5 meter in the work-circuit B L L b will indicate when the pressure in the work-circuit is thus decreased by the introduction of another fifth of the load, and the regulating-circuit B R bwill then be closed through resistance R, which will be adjusted to bring the pressure at the point I) nearer to the pressure in the brush B, and thereby bring the pressure in the work circuit to the proper standard. When a third fifth of the loadLis introduced, the pressure in the work-circuit again decreases and is again brought to the standard by aid of the regulating-circuit by still further decreasing the resistance R, and so on until the whole load is in the work-circuit, when the resistance R is eliminated, or practically so, the work-circuit then being from brush B to brush B, practically as if the brush B and resistance B were not present. My theory is that with maximum load the diiference of potential between the main brush B and the junction Z) is at the minimum, the resistance R being then so small as to cause but slight fall of potential, there being but slight difference of potential between B and Z) under full load. hen the aditional resistance is thrown into the work-circuit, other conditions being the same, less current flows through the entire circuit, including the armature coils, and hence there is a greater difference of potential between the terminals of the machine; but the potential or pressure at the junction Z) will be kept constant, for the reason that b is connected directly to the brush B and through resistance R to brush B, for the pressure at junction 1) can be made substantially the same as the pressure in brush B by eliminating resistance R, or can be made substantially the same as the pressure in brush B by making resistance R infinite, and can be made more than in B and less than in B by varying resistance R. For extreme range of regulation the brush B may be drawn toward the brush B, or the brush B can be moved toward B as indicated by dotted line B.

Theoretically, as I understand the matter, with a constant speed and a constant current through the field-circuit B F F I), the differ ence of potentialbetween the terminals of the dynamo is at the minimum under full load when in multiple, an d increases Whenever the load is reduced, this being, as I understand it, because of the decreasing reaction of the armature upon the fielda'nagnets as the currentin the armature decreases, which practically makes the field stronger, even though the on rrent in the field-circuit B F F Z) remain eonstant; and I therefore connect the junction 1) between the field and Work circuits with both brushes B B and I am thereby enabled to maintain the pressure constant at 7), Whatever be the change in the load.

That I claim as my invention is- In a dynamo, the additional brush E the main brushes B B, and the adjustable resist ance R, additional brush 13 being connected directly to the conductors forming the orkcircuit and the conductors forming the fieldcircuit, and the brush B connected to the conductors through adjustable resistance R, all 

